Process and apparatus for making coke of even size

ABSTRACT

A CORE CLAMPING SYSTEM FOR USE WITH NUCLEAR REACTORS A PROCESS FOR PRODUCING COKE OF SUBSTANTIALLY EVEN-SIZE PIECES FROM CAKING COALS WHICH IN COKING YIELD A COHERENT WHEREIN BIMETALLIC ELEMENTS ARE PLACED AROUND A CORE SO THAT IN HIGH TEMPERATURE AND FLUX CONDITIONS THEY ACT CAKE, WHICH COMPRISES EMBEDDING MATERIALS IN LOCALLY CONCENTRATION AMOUNTS INTO THE COAL TO BE COKED CAPABLE EXERT AN INWARDLY DIRECT CLAMPING FORCE ON A PREDETERMINED CLAMPING PLANE THEREBY COUNTERACTING THE TENDENCY OF WEAKENING THE COHERENCE OF THE CAKE AT PREDETERMINED PLACES, THEREBY SUBDIVIDING THE CAKE AND RENDERING POSFOR TE CORE TO EXPAND UNDER THOSE CONDITIONS AND MAINTAINING CONSTANT CORE GEOMETRY. SIBL ITS BREAKING UP INTO EVEN-SIZE PIECES UPON DISCHARGE FROM THE COKING CHAMBER. THE INVENTION ALSO COMPRISES AN APPARATUS FOR CARRYING OUT THE PROCESS.

Aug. 21, 1973 w WENZEL ET Al. 3,753,866

PROCESS AND APPARATUS FOR MAKING COKE OF EVEN SIZE Filed Aug. 21. 1970 3 Sheets-Sheet 1 can .sraenai q Sax OPE 5704.461!

cow/N4 (/44 M5 2,? no 74 7454:

J A I; /6 Ram-r3545 FIGZ if IN VENTOR$ A T ORNE Y5 Aug. 21, 1973 w. WENZEL ET AL 3,753,866

PROCESS AND APPARATUS FOR MAKING COKE OF EVEN SIZE Filed Aug. 21L. 1970 5 Sheets-Sheet 2 ATTORNEKT Aug. 21, 1973 w. WENZEL ET AL 3,753,865

AND APPARATUS FOR MAKING COKE OF EVEN SIZE PROCESS 3 Sheets-Sheet 3 Filed Aug. 21. 1970 7'0 COKE OVi/V 5 NH 2 N 4/ 275A 1 MW CC FIG. 7

FIG. 7A

United States Patent 3,753,866 PROCESS AND APPARATUS FOR MAKING COKE 0F EVEN SIZE Werner Wenzel, Hermann Schenck, Heinrich-Wilhelm Gudenau, and Enno Wieting, Aachen, Germany, assignors to Firma Carl Still Filed Aug. 21, 1970, Ser. No. 65,935 Claims priority, application Germany, Aug. 28, 1969, P 19 43 763.9 Int. Cl. Cb 45/02, 53/08 US. Cl. 201-6 3 Claims ABSTRACT OF THE DISCLOSURE FIELD OF THE INVENTION The invention relates to a process and apparatus of making coke the individual pieces of which are of even size.

For many purposes for which coke is to be used, some of which are among the most important ones, the manufacture of coke of even size is paramount. This is particularly true in the case of coke made from coal that has a tendency to caking. Thus, for the use in blast furnaces, it has proved to be especially advantageous to use pieces of coke of an even size of about 30-40 mm. Even when coke of larger size is used, such as size 40/50 mm. or 50/60 mm., it is preferable to keep these sizes in limits as small as possible.

When such coke in pieces of even size is to be produced in horizontal chambers, in accordance with the conventional coking method, the only possibility to accomplish the desired results is, up to now, to break off oversize grains and remove undersize pieces by screening. This method is, however, uneconomical, since a combination of breaking and screening pieces of undesired size involves considerable labor and expenses incurred thereby, rendering at the same time the output in coke of satisfactory even size too low. It is necessary to tolerate 20 or 30 or even higher percentages of undersize pieces and it is an added inconvenience that such pieces, if they are marketable at all, will at best have to be sold at lower prices than coke of the desried even size.

SUMMARY OF THE INVENTION It is the object of the present invention to provide a method and apparatus by which the shortcomings of known methods in the production of coke having pieces of even size can be overcome.

It is a further object to provide a method and apparatus by which even-size coke can be produced directly and without waste, thereby rendering the method according to the invention highly economical.

Other objects and advantages of the invention will become apparent from the following detailed description and from the accompanying drawings.

According to the invention a horizontal-chamber coke oven is used as heretofore; however, due to novel arrangemerits, even-size coke is produced at high yields, while the inevitably occurring production of undersize pieces is cut down considerably and ranges far below the quantity obtained in the production by known methods.

3,753,866 Patented Aug. 21, 1973 In order to achieve this end, the invention provides means for obtaining pieces of coke of even size by subdividing the cake of coke during its formation into pieces of about the same size by embedding locally arranged compacted substances or materials which weaken the coherence of the cake of coke leaving the coking chamber at given spots or along given lines, so that the cake will break apart at the determined places.

As suitable substances for embedding in the cake, iron ores have proved of special advantage. Of the several iron ores available, hematitic ores have been observed to perform best; these ores are known to destroy the bitumen which causes caking, when they contact coal to be coked at coking temperature.

The weakening of the coherence of the cake of coke can be so adjusted by local embedding of iron ores in the cake of coke that most of it will break apart already at the time when the coke is discharged from the chamber and will directly form even pieces. In another mode of operation, the cake of coke exhibits a certain coherence at the time of discharge from the coking chamber, so that an after-treatment in a dividing device will have to follow in which subdivision into pieces of even size is effected. According to the invention, such a dividing device may, e.g. consist of a transit drum through which the cake of coke is passed and in which by rolling along the walls a force is brought to bear on the cake which will cause it to break up into the pieces of determined size.

Local concentration of substances weakening the coherence of the cake of coke can be eifected in various ways, according to the invention. One method consists in distributing the pieces of ore with a grain size of e.g. 10-20 mm. as evenly as possible in the layer of coal to be coked. When in the production of the cake of coke the latter undergoes a strain, there exists a statistic probability that breaking apart will occur along the pattern of embedded grains of e.g. iron ore.

In general it may be diflicult to achieve the desired uniform distribution of the grains of ore without using special measures. A particular measure of the present invention consists in introducing the coal to be coked into the coking chamber in the form of pellets. Such coal pellets may be made from moist fine coal in conventional pelletizing devices, e.g. pelletizing plates or dishes.

In the present case, pieces of iron ore are placed into the pelletizing device, for instance, pelletizing dish which pieces serve as core for the coal pellets to be formed and are embedded in the finished pellet approximately in the center. When such coal pellets have been charged into the coking chamber and the size of the pellets is for instance, of an even 40 mm., there will be formed a uniform net of iron ore pieces in the layer of coal to be coked, the pieces having a distance of their centers of about 40 mm., in accordance with the present example.

A further method according to the invention for the embedding of locally concentrated materials in the coal to be coked, consists again in making coal pellets from moist fine coal; however, in this case, a layer of fine ore, e.g. iron ore, is applied to the surface of the coal by pelletizing, forming a shell enclosing the coal. This may be done in a manner known per se by applying a rim of powder onto a pelletizing dish for fine coal pelletizing, wherein the powder rim is charged with the suitable fine ore.

Another method for making shell pellets, which is likewise known, consists in passing coal pellets made in one pelletizing dish, into a second pelletizing dish charged with fine ore.

The shell pellets introduced into the coking chamber, are deformed during the coking process in such a manner that they will fill the chamber space practically completely. In the ideal case, dice-shaped pieces of coke will result, which are kept separated from each other by the sheet of fine ore applied thereto by pelletization and likewise undergoing deformation in the coking chamber.

It may be advantageous to charge into the coking chamber both pieces of ore, and layers or shells of fine ore, as explained in the description of the above methods. In that manner, a larger amount of ore is introduced into the coke. Particularly for the production of even-size blast furnace coke it is desirable to use a coke with a higher iron ore or iron sponge content, thus obtainable; this may result in a lower coke consumption during the smelting process.

In cases in which it is undesirable to have iron ore or iron present in the final coke product, or present in only small amounts, the process according to the invention may be carried out in such a manner that the embedded material for weakening the coherence of the cake may consist of lean coal, anthracite or small pieces of broken coal in addition to iron ore or instead of it.

In some cases it may be desirable to add another layer or shell of a coherence-weakening material to the ore shell applied to the coal pellet. Such a procedure will be especially advisable when thicker shells of ore, which are desirable for producing ore coke, cause a sintering of the formed sponge iron and thereby make the breaking-up of coke into even pieces more difiicult. Such additional shells made by pelletizing, may consist, e.g. of lean coal or chalk.

For bringing about an even distribution of the material weakening the coherence, other methods than pelletizing may be used for the preliminary shaping of the fine coal. We may mention, e.g. briquetting of the fine coal, the process being carried out without binding agent for economical reasons and in view of the low strain to which the briquettes are subjected. As regards the addition of materials which weaken the coherence, the briquettes are used in the same manner as explained above for pellets.

Since fine coal is frequently present in economical form as coal sludge or coal paste, it is advantageous to proceed according to the invention by pre-shaping the filter cake obtained when filtering the coal sludge through suction filters. Such pre-shaping may e.g. be carried out in a manner known per se by placing on the suction filter a so-called honeycomb band into the honeycombs of which the coal passes while drying and from which it is recovered in the corresponding pieces. These pieces of coal are then processed as described above in the pelletizing procedure, in order to embed the substances for weakening the coherence.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings, several embodiments of the device for carrying out the invention are illustrated schematically.

FIGS. 1 and 2 show different parts of the same device;

FIG. 3 illustrates the coking chamber of the device with parts broken away to show the interior filled with coking material;

FIGS. 4 to 6 show the structures of difierent fillings;

FIG. 7 illustrates an embodiment of the so-called honeycomb arrangement; and

FIG. 7A shows the honeycomb belt.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS. 1 and 2, numeral 10 is a storage bin for coal and 12 one for ore. Both coal and ore are ground to grain size of 1 mm. and the coal in bin 10 has been dried to a moisture content of 16% by weight.

The moist coal is passed onto a rotating pelletizing dish 13 by means of an oscillating conveyor (not shown); by its rotation, dish 13 forms the fine coal powder into pellets 23, which are then spilling over into the rimmed portion 14 of the dish where they are coated with a layer of fine iron ore. The ore-coated pellets tumble subsequently onto a conveyor device 15 which is capable of being lifted and lowered and whose belts 23a, 23b are driven in a circular course in the directions shown by arrows, thereby transporting the pellets into a coking chamber 16. The coking chamber 16 has two stationary walls 25 and two removable walls 21a, 21b. The wall 21a is shown in the position closing the chamber at the coke discharge end, while the other one, wall 21b, has been taken out and replaced by an insert 22 having a large filling opening for coal admission. In the embodiment shown in FIG. 2, the walls are shown as sliding plates, but this is only an example, there are many other ways of making removable wall pieces which could be applied.

After the chamber 16 has been filled, insert 22 is removed and the wall 21b put in place for closing the chamber, whereupon the coking operation is carried out.

FIG. 2 illustrates the discharge of coke from chamber 16. Both walls 21a and 211; have been removed and an expelling device 17 has been moved in, which forces pieces of coke 18 out of chamber 16. Red-hot coke is dropped over chute 24 into an open drum 19 which rotates in the sense indicated by arrow 27, while coke passes through the drum. The strain to which the coke is subjected during the passage under notation, causes the coke to break up into evenly formed pieces 20 which are then quenched.

FIG. 3 shows in perspective, with parts broken away a coking chamber 16a, having removable end walls 21c and 21d with a filling that is somewhat different from the one described with reference to FIGS. 1 and 2. Herein, fine ore particles 31 are embedded in coal 32. The particles 31 consist of evenly distributed grains of hematite of 10- 20 mm. size. This is brought about by mixing fine coal and hematite grains before the chamber is filled by one of the known filling devices (not shown). Parts of the discharge elements of the device are not shown because they are similar to the ones illustrated in FIG. 2. A number of ore .particles which serve as means for breaking up the coherence of the coke, become separated during the discharge and may be removed by screening, before the coke is quenched.

FIGS. 4 to 6 illustrate different structures of the pellets according to the invention. In FIG. 4, designates the coking chamber in which the pellets are contained. The pellets are shown to consist of a core of iron ore 31a surrounded by fine coal 32a. Such pellets are made on a pelletizing dish which has no powder rim comparable to the one shown in FIG. 1. The size of the pellets is e.g. 10-20 mm. If iron pieces and moist fine coal are mixed in the coal bin and passed to the pelletizing dish together, pellets are formed having a core of ore as shown. The coking procedure is the same as described with reference to FIGS. 1 and 2.

FIG. 5 shows the coking chamber indicated as 16d filled with pellets having a body of coal 31b and a shell 32b of finely ground iron ore. These are made according to the description of FIG. 1.

FIG. 6 shows the coking chamber indicated at 16c filled with pellets 31c of coal in a double shell: a shell 32c consisting of finely ground iron ore, and a shell 35 consisting of finely ground chalk. The latter shell almost completely prevents the baking together of the pellets during the coking. Such pellets may be made in pelletizing dishes having two powder rims.

FIGS. 7 and 7A show the so-called honeycomb arrangement of the device for conveying ore-coated coal to the coking chamber. An endless compartmented band or belt 36 is passed over a suction filter 39 divided into a plurality of cells 42, and is returned over a direction changing star-shaped member 46. The filter is mounted for rotation on a shaft 52 in the sense indicated by arrow 37. With the belt 36, the filter dips into a sludge 38 of coal and water contained in a tank 48. Arrows 43 indicate that water is sucked into the interior through the filter, from which it is drained. Due to the honeycomb structure of the belt, the coal taken up by the belt as it passes through the sludge, becomes deposited on the belt in subdivided form and as it is carried below a bin 41 filled with ore 39', a distributing device (not shown) sprays the finely ground ore onto the belt; then, while the latter passes over the direction changing element 46, evenly shaped pieces 50 are dropped on the conveyor belt 49, which transports them into the coking chamber.

In the following, the method according to the invention will be described more fully in two examples, which are given by way of illustration and not of limitation. Many changes and modifications in the details can be made without parting from the spirit of the invention.

Example 1 A coking coal of the Ruhr valley, Germany, of the following composition, is coked in an experimental coking plant.

Composition (percentages by weight):

Water 8.5 Volatile ingredients 23.3 Ashes 6.88 Carbon Balance The coking time is 6 hours. The final product shows the following analysis result for grain size in weight percent:

In this case, only 7% of the coke obtained has the de sired size of 30-40 mm.; the amount of undersized pieces is 13%, oversized 80%.

Example 2 The same coking coal as used in Example 1, was comminuted to size -1 mm. The finely ground coal having a moisture content of 16%, is pelletized on a pelletizing dish; the size of the pellets is 40 mm. The coal pellets are then coated in a similar pelletizing dish with a shell of iron ore, consisting of hematite having a grain size 0-1 mm. The thickness of the shell applied by pelletizing is 0.1 mm. on the average.

These ore-coated shell pellets are coked under the same conditions as described in Example 1. The cake of coke obtained was charged into a rolling drum and tumbled at 10 revolutions. Thereby, the cake was broken up into the following size of grains:

Percent Even-size pieces of 30-40 mm. 92 Undersize grains, mm. 8

The method described carried out according to the present invention may undergo the following modifications, using various coking processes known per se.

Among others, it is possible to use for the present purpose the grid coking process by Wenzel/Schenck, the inventors of the present process. In their prior process, ducts for gas passage are provided within the layer of coal to be coked, the gases generated during the coking process being burnt in said ducts. When the process of the invention is applied to the above mentioned known method, materials are embedded in locally concentrated form into the layers of coal to be coked, which materials have the purpose of weakening the coherence of the coke, as explained, and to cause the formation of pieces of even size.

In the use of the present invention for producing coke in horizontal chambers there exists the important requirement of maintaining a sufliciently high coherence of the coked cake in order to make a flawless discharge of the coke by expelling possible without breakage. While it is possible to keep the several pieces of coke separated in the chamber by providing sufiiciently thick shells of ore on the coal pellets, it is a requirement when working in conventional coke ovens to see to it that a minimum coherence is maintained. These apparently contradictory requirements are fulfilled when coal pellets with a diameter of about 40 mm. are coated with shells of about 0.05-1 mm. hematite ore.

What is claimed is:

1. An apparatus for producing coke of substantially even-size pieces from a sludge containing coal and water, which comprises a coking chamber, a sludge container, means for picking up sludge from the container, draining water from the sludge, and conveying it in form of shaped pieces to said coking chamber, said means comprising a rotary suction filter mounted on a drive shaft above the sludge container for part immersion in said sludge, an endless compartmented band carried on said suction filter for movement therewith, designed to pick up sludge and deposit it in the compartments in substantially even proportions as it moves through the sludge, which is being drained of water by the action of the suction filter during the movement of the band, so that coal remains in the compartments in even amounts, said apparatus mounted above the path of the moving band, further comprising a container for fine-grained ore, distributing means associated with said ore container adapted to spray ore on the coal in the compartments as the band passes below the ore container, means mounted ahead of the ore container in the sense of travel of the band, for changing the direction of the band and return it toward the sludge container, said direction changing means having, arranged on its circumference, spikes appropriately spaced to receive the shaped pieces of ore-covered coal from the compartments of the band, and conveyor means for transporting the pieces to the coking chamber as they are dropped from the band during direction change.

2. A process for producing coke in pieces of predetermined size from caking coals Which in coking yield a coherent cake, which comprises forming the coal to be coked into a plurality of individual uniform coherent masses and embedding materials in locally concentrated amounts into the coal to be coked, heating the coal with the embedded materials to form it into a coke cake having weakened areas at the locations of the materials capable of weakening the coherence of the cake at these locations, subdividing the cake by subjecting it to movement and impact to cause it to break along the weakened areas into pieces of predetermined size upon discharge from the coking chamber, the materials embedded in the coal consist of hematite or another iron ore of a grain size ranging from 10-25 mm., said pieces of ore in finely ground form being coated onto pieces of coal in the form of pellets, so as to form a shell thereon, said pellets being charged into a coking chamber with external heating, and applying another shell of chalk or lean coal onto the shell of the ore for preventing the sintering of said first shell.

3. A process for producing coke in pieces of predetermined size from caking coals which in coking yield a coherent cake, which comprises forming the coal to be coked into a plurality of individual uniform coherent masses and embedding materials in locally concentrated amounts into the coal to be coked, heating the coal with the embedded materials to form it into a coke cake having weakened areas at the locations of the materials capable of weakening the coherence of the cake at these locations, and subdividing the cake by subjecting it to movement and impact to cause it to break along the weakened areas into pieces of predetermined size upon discharge from the coking chamber, said fine moist coal comprising a sludge, said sludge being filtered with suction to remove the Water therefrom and the coal is then transported on a honeycomb band being thereby subdivided into even-size pieces, onto which finely grained coating sheets of ore are applied during the transport to the coking chamber.

References Cited UNITED STATES PATENTS 8 Curran 201-22 Reed et a1. 201-23 Komline 210-77 Heinze et a1. 201-6 Tufty 201-5 Becker 201-23 Creglow 201-6 Horton et a1 210-77 U.S. C1. X.R. 

